Messages in this thread | | | Date | Wed, 9 Nov 2011 16:13:37 +0100 | From | Niklas Söderlund <> | Subject | Re: [PATCH] amd64_edac: fix size decoding error on K8 |
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On 11/09/2011 03:42 PM, Borislav Petkov wrote: > On Wed, Nov 09, 2011 at 03:32:58PM +0100, Niklas Söderlund wrote: >> Use a lookup table to calculate the size of a chip select. The old >> method of calculating size return erroneous values for some memory >> configurations. > > Can you elaborate more on those erroneous values, please? > > Thanks. >
The decoding table from the documentation:
cs_mode size (mb) 0 32 1 64 2 128 3 128 4 256 5 512 6 256 7 512 8 1024 9 1024 10 2048
The original code:
if (cs_mode == 3 || cs_mode == 8) return 32 << (cs_mode - 1); else return 32 << cs_mode;
The code tries to compensate for the irregularity in the decoding table but fails for cs_mode greater or equal to 4. It fails because:
- It do not consider the cumulating effect of reoccurring sizes for all values of cs_mode. It only tries for the special cases and it only succeeds in one.
- It do not consider the out of order values of cs_mode values 4-7: 256, 512, 256, 512.
Best Regards // Niklas -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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